SPANA / Making a diagram

Example of a diagram where reversed concentration ranges are used. The diagram shows the species distribution for Fe³⁺ when chloride is exchanged for sulphate. Note that both Cl⁻ and SO₄²⁻ are varied along the X-axis, although only one component is shown in the X-axis of the diagram. The composition changes from 0.4 M HCl at the left of the diagram to 0.2 M H₂SO₄ at the right (see last two lines of the input file below). The ionic strength is evaluated iteratively at each point.

This diagram was obtained with the following input file:

 4 15 5 0
H+,  Fe 3+,  SO4 2-,  Cl-
Fe(OH)2+      , -4.8    -2 1 0 0  Fe(OH)3       , -12     -3 1 0 0
Fe(OH)4-      , -21.6   -4 1 0 0  Fe(SO4)2-     ,  6.22    0 1 2 0
Fe2(OH)2+4    , -2.82   -2 2 0 0  Fe3(OH)4+5    , -6.3    -4 3 0 0
FeCl+2        ,  1.52    0 1 0 1  FeCl2+        ,  2.22    0 1 0 2
FeCl3         ,  1.02    0 1 0 3  FeCl4-        , -0.98    0 1 0 4
FeOH 2+       , -2.15   -1 1 0 0  FeSO4+        ,  4.25    0 1 1 0
H2SO4         ,  0.78    2 0 1 0  HSO4-         ,  1.982   1 0 1 0
OH-           , -14.002 -1 0 0 0  Fe(OH)3(s)    , -3.03   -3 1 0 0
Fe2(SO4)3(cr) , -0.19    0 2 3 0  Fe2O3(cr)     ,  0.1    -6 2 0 0
FeOCl(cr)     , -4.55   -2 1 0 1  FeOOH(cr)     , -0.17   -3 1 0 0
Fe 3+, Cl-,
T, 0.4  T, 1E-5
TV, 0   0.2
TV, 0.4   0